574 Abstract Report of Agricultural Discussions. 
56,352,000 acres, tliere is believed to be 22,890,000 acres of wet land 
capable of improvement by drainage, including sucb jjroportion as 
has already been drained, and that these wet lands are nearly equally 
divided between those characterised as " clays " and those called 
" free soils." The extent of land already permanently drained does 
not exceed 1,700,000 acres, and of these much the larger part are 
clays, so that there remain upwards of 21,000,000 of acres yet to be 
drained, besides lands incapable of improvement. There is a very 
general belief that much more under-draining has been done than a 
careful consideration of facts corroborates. There has been so miich 
said and wi'itten on drainage of late years, and the red colour of the 
pipes as they appear in the fields, like the scarlet petticoat and scarlet 
cloak that have become so fashionable, make such a display as v/c 
travel along, that we can readily imderstand how the erroneous im- 
pression has become general. Very few words will satisfy all doubt 
•upon the point. The utmost extent of land drained under the Public 
and Private Moneys' Acts, and under the several Drainage Companies' 
Acts, cannot exceed 1,100,000 acres, as the total outlay up to the 
present time does not reach 6,000,000/. The di-ainage of a permanent 
character executed by landoMTiers with private funds, though very 
laigcly increasing, is still much less than the extent done with 
borrowed capital, and at the present rate of progress it may fau-ly be 
assumed that it will take at least a centiu:y to complete the imder- 
drainage of the country. To illustrate our present capability to 
proceed with under-drainage, it may be mentioned that the number of 
pipe-yards, or brick-yards making pipes, in Great Britain, is estimated 
at 2800 ; and if we assume the number of pipes made at each yard to 
be on the average 150,000 a-year, the total number made in the year 
may be taken at -120,000,000. The number of pipes now used in 
under-draining may be taken at an average of 1250 pipes per acre, 
and dividing the quantity made by this average we see that 336,000 
acres might be drained per annum ; but as a large portion of the 
pipes made are applied to temporary, shallow, and unconnected works, 
it is not possible to ascertain from such data the extent of permanent 
di'ainage executed. Assuming, however, that a quarter of a million of 
acres will, in future, be permanently drained per annum, we may see 
that a century will jDass ere the work is completed. If such is our 
statistical position with respect to execution, what has been the 
prcgi'css and what om- present state of knowledge in the science of 
undcr-drainage itself? These questions will be best answered as we 
proceed, and their importance will be recognised in their bearing upon 
the gi'cat national object of our water economy. 
The first effort in the way of agiicultural drainage was the raising 
of the surface of wet land into the form of " ridge and furrow." This 
may bo called the aboriginal mode. Tlic second step was the placing 
of bush drains under the fm-rows, at a depth just sufficient to conduct 
the water under groimd, rather tlian along the surface of the furrow. 
The third step was the substitution of horse-shoe drains and pipes for 
bushes, still following the aboriginal furrows. The fourth step was 
that taken by Smith of Dcanston, upon his farm near Stirling, in a 
